1. Field of the Invention
The present invention relates to a laser beam machining apparatus and in particular, to a laser beam machining apparatus having an improved throughput and an improved machining accuracy.
2. Description of the Related Art
Conventionally, there is a known laser beam machining apparatus called "laser repair" for cutting a fuse for switching an LSI internal wiring or a defective circuit to a redundant circuit, for example, in a DRAM. This laser beam machining apparatus applies a beam focus spot of about 2 micrometers to scan a wafer surface with accuracy in the order of sub-micrometer at a high speed, thus cutting a predetermined position.
Such a laser beam machining apparatus comprises a laser oscillator for emitting a laser beam, and a stage movable in two-dimensional directions of XY with an object such as a wafer mounted thereon. A laser beam emitted from the laser oscillator is focused on the object to be machined (hereinafter, referred to as a workpiece).
The laser beam machining apparatus further comprises a central processing unit (CPU) for performing various controls according to a program, so as to apply a laser beam from the laser oscillator onto a plurality of machining points pre-specified on the workpiece mounted on the stage. In general, positioning of the stage is controlled so that the laser beam is applied to a predetermined machining point on the workpiece.
Conventionally, there has also been an attempt to improve the throughput by accelerating the stage for an interval between machining points.
However, with the rapid technical progress, more and more fine machining is required with an increasing number of machining points.
The laser beam machining apparatus also needs to further increase its machining accuracy and further improve the throughput.